A123262 Fibonacci-tribonacci triangle.

0, 0, 1, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 3, 0, 0, 0, 0, 2, 5, 0, 0, 0, 0, 0, 5, 8, 0, 0, 0, 0, 0, 1, 10, 13, 0, 0, 0, 0, 0, 0, 3, 20, 21, 0, 0, 0, 0, 0, 0, 0, 9, 38, 34, 0, 0, 0, 0, 0, 0, 0, 1, 22, 71, 55, 0, 0, 0, 0, 0, 0, 0, 0, 4, 51, 130, 89, 0, 0, 0, 0, 0, 0, 0, 0, 0, 14, 111, 235, 144

Offset: 0

Author

Philippe Deléham, Nov 06 2006

Keywords

• nonn
• tabl

Comments

Or, skew Jacobsthal-Lucas triangle, read by rows.

Examples

			Triangle begins:
.0;
.0, 1;
.0, 0, 1;
.0, 0, 0, 2;
.0, 0, 0, 1, 3;
.0, 0, 0, 0, 2, 5;
.0, 0, 0, 0, 0, 5, 8;
.0, 0, 0, 0, 0, 1, 10, 13;
.0, 0, 0, 0, 0, 0, 3, 20, 21;
.0, 0, 0, 0, 0, 0, 0, 9, 38, 34;
.0, 0, 0, 0, 0, 0, 0, 1, 22, 71, 55;
.0, 0, 0, 0, 0, 0, 0, 0, 4, 51, 130, 89;
.0, 0, 0, 0, 0, 0, 0, 0, 0, 14, 111, 235, 144;
		

Crossrefs

Cf. A037027.

Formula

T(n,k)=T(n-1,k-1)+T(n-2,k-2)+T(n-3,k-2), T(n,0)=0, T(1,1)=1, T(n,k)=0 if k<0 or if k>n . T(n,n)= Fibonacci(n)=A000045(n) . Sum_{k, 0<=k<=n}T(n,k)=A000073(n+1), tribonacci numbers . Sum_{n, n>=k}T(n,k)=A001045(k), Jacobsthal sequence.